JPH04253063A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the electrophotographic sensitive body high in sensitivity and superior in characteristics against repeated uses by incorporating a specified hydrazone compound as an electric charge transfer material in a photosensitive layer. CONSTITUTION:The electrophotographic sensitive body is formed by laminating on a conductive substrate 1 a photosensitive layer 20 containing as the charge transfer material the hydrazone compound represented by formula I in which each of R1 and R2 is H, halogen, or alkyl; each of R3 and R4 optionally substituted alkyl or aryl or alkenyl; each of R5 and R6 is H, alkyl, or aryl; and each of R7 and R8 is optionally substituted alkyl, such aryl, such alkenyl, or such thenyl.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a photosensitive layer of an electrophotographic photoreceptor, and more particularly to a charge transporting material for a photosensitive layer having excellent sensitivity.

0002

[Prior Art] Conventionally, photosensitive materials for electrophotographic photoreceptors (hereinafter also referred to as photoreceptors) have been made of inorganic photoconductive substances such as selenium or selenium alloys, and inorganic photoconductive substances such as zinc oxide or cadmium sulfide. dispersion in a binder, an organic photoconductive material such as poly-N-vinylcarbazole or polyvinylanthracene, a dispersion of an organic photoconductive material such as a phthalocyanine compound or a bisazo compound in a resin binder; or vacuum-deposited materials are used.

[0003]Also, a photoreceptor must have the function of retaining a surface charge in the dark, the function of receiving light and generating a charge, and the function of receiving light and transporting a charge. So-called single-layer photoreceptors have these functions in one layer, and the other is a layer that is functionally separated into a layer that mainly contributes to charge generation and a layer that contributes to surface charge retention in the dark and charge transport during light reception. There is a so-called laminated type photoreceptor in which two types of photoreceptors are laminated. For example, the Carlson method is applied to image formation by electrophotography using these photoreceptors. Image formation in this method involves charging the photoconductor in a dark place by corona discharge, forming an electrostatic latent image such as text or pictures on the original on the surface of the charged photoconductor, and forming an electrostatic latent image on the surface of the charged photoconductor. After the toner image has been transferred, the photoreceptor is subjected to static electricity removal, removal of residual toner, photostatic static removal, etc. before being reused. be done.

[0004] In recent years, many applications of photoconductive organic compounds with excellent charge transport ability to photoreceptors have been proposed due to their advantages such as flexibility, thermal stability, and film-forming properties. For example, as an oxadiazole compound, US Pat. No. 318,944
Specification No. 7, as a pyrazoline compound, Japanese Patent Publication No. 59-2
No. 023, and as a hydrazone compound, Japanese Patent Publication No. 5
Various charge transport materials are known from Japanese Patent Application Laid-open No. 5-42380, Japanese Patent Application Laid-Open No. 57-101844, Japanese Patent Application Laid-Open No. 54-150128, etc.

[0005]

[Problems to be Solved by the Invention] As mentioned above, organic materials have many advantages that inorganic materials do not have, but at the same time, it is difficult to obtain a material that fully satisfies all the characteristics required of an electrophotographic photoreceptor. At present, there are no such products, and there are problems particularly with photosensitivity and characteristics during repeated and continuous use.

The present invention has been made in view of the above points, and by using a new organic material that has never been used as a charge transport material in the photosensitive layer, high sensitivity and excellent repeatability can be achieved. The purpose of the present invention is to provide an electrophotographic photoreceptor for copying machines and printers.

[0007]

[Means for Solving the Problems] According to the present invention, the above-mentioned object has a photosensitive layer on a conductive substrate, and the photosensitive layer contains a hydrazone compound represented by the general chemical formula (I) as a charge transport substance ( In the formula, R1 and R2 are hydrogen atoms, halogen atoms, alkyl groups, R3 and R4 are substituted or unsubstituted alkyl groups, aryl groups, alkenyl groups, R5 and R6 are hydrogen atoms, alkyl groups, aryl groups, R7 and R8 represents a substituted or unsubstituted alkyl group, aryl group, alkenyl group, or thenyl group).

[0008]

[Case 2]

The general chemical formula (I) used in the present invention
The hydrazone compound can be synthesized by a conventional method. That is, it can be easily synthesized by dehydrating and condensing an aldehyde represented by the following general chemical formula 13 and a hydrazine represented by the following general chemical formula 14 in an appropriate organic solvent (e.g. ethanol, etc.) in the presence of a catalyst such as an acid. be able to.

0010

[Chemical formula 3]

Specific examples of the hydrazone compound represented by the general chemical formula (I) thus obtained are illustrated in Chemical formulas 1 to 12.

0012

[C4]

[0013]

[C5]

The photoreceptor of the present invention contains the above-mentioned hydrazone compound in the photosensitive layer, and depending on how these hydrazone compounds are applied, the photoreceptor may have the following properties as shown in FIG. 1, FIG. 2, or FIG. 3. It can be used for.

1 to 3 are conceptual cross-sectional views of the photoreceptor of the present invention, in which 1 is a conductive substrate, 20, 21, 22 are photosensitive layers, and 3
is a charge generation material, 4 is a charge generation layer, 5 is a charge transport material,
6 is a charge transport layer, and 7 is a coating layer.

FIG. 1 shows a photosensitive layer 20 (usually referred to as a single-layer photoreceptor) in which a charge generating substance 3 and a hydrazone compound as a charge transporting substance 5 are dispersed in a resin binder on a conductive substrate 1. configuration) is provided.

FIG. 2 shows a charge generating substance 3 on a conductive substrate 1.
A photosensitive layer 21 (commonly referred to as a laminated photoreceptor) is provided, which is a laminated structure of a charge generation layer 4 mainly composed of a charge-generating layer 4 and a charge-transport layer 6 containing a hydrazone compound as a charge-transporting substance 5. be.

FIG. 3 shows an inverse layer structure to that shown in FIG. In this case, it is common to further provide a coating layer 7 to protect the charge generation layer 4.

The reason why the two types of layer configurations shown in FIGS. 2 and 3 are used is that even if the layer configuration shown in FIG. 2, which is normally used in a negative charging system, is used in a positive charging system, it is difficult to find a compatible charge transport material. This is because the layer structure shown in FIG. 3 is required at this stage as a positive charging type photoreceptor.

The photoreceptor shown in FIG. 1 can be prepared by dispersing a charge generating material in a solution containing a charge transporting material and a resin binder, and applying this dispersion onto a conductive substrate.

The photoreceptor shown in FIG. 2 is produced by vacuum-depositing a charge-generating substance on a conductive substrate, or by applying a dispersion obtained by dispersing particles of a charge-generating substance in a solvent or a resin binder, and drying the resulting material. It can be created by applying a solution containing a charge transport substance and a resin binder thereon and drying it.

The photoreceptor shown in FIG. 3 is produced by coating a conductive substrate with a solution containing a charge transporting substance and a resin binder and drying it, and then vacuum-depositing a charge generating substance thereon, or by depositing charge generating substance particles thereon. It can be created by applying a dispersion obtained by dispersing it in a solvent or a resin binder, drying it, and further forming a coating layer.

The conductive substrate 1 serves as an electrode of the photoreceptor and at the same time serves as a support for other layers, and may be cylindrical, plate-shaped, or film-shaped, and may be made of aluminum, stainless steel, It may also be made of metal such as nickel, glass, resin, etc., which has been subjected to conductive treatment.

The charge generation layer 4 is formed by applying a material in which particles of the charge generation substance 3 are dispersed in a resin binder as described above, or by a method such as vacuum evaporation, and receives light to generate charges. occurs. In addition to the high charge generation efficiency, the ability to inject the generated charges into the charge transport layer 6 and the coating layer 7 is also important, and it is desirable that the charge is less dependent on the electric field and can be easily injected even in a low electric field. As charge-generating substances, phthalocyanine compounds such as metal-free phthalocyanine and titanyl phthalocyanine, various azo, quinone, and indigo pigments, dyes such as cyanine, squarylium, azulenium, and pyrylium compounds, and selenium or selenium compounds are used to form images. A suitable material can be selected depending on the light wavelength range of the exposure light source used. Since the charge generation layer only needs to have a charge generation function, its thickness is determined by the light absorption coefficient of the charge generation substance and is generally 5 μm or less, preferably 1 μm or less. The charge generation layer is mainly composed of a charge generation substance, and a charge transporting substance can also be added thereto. As the resin binder, appropriate combinations of polycarbonate, polyester, polyamide, polyurethane, vinyl chloride, phenoxy resin, polyvinyl butyral, epoxy, diallyl phthalate resin, silicone resin, methacrylic acid ester polymers and copolymers may be used. is possible.

The charge transport layer 6 is a coating film in which a hydrazone compound represented by the general chemical formula (I) as an organic charge transport substance is dispersed in a resin binder, and acts as an insulating layer in the dark to absorb the charges on the photoreceptor. It functions to hold and transport charges injected from the charge generation layer when receiving light. As the resin binder, polycarbonate, polyester, polystyrene, polymers and copolymers of methacrylic acid ester, etc. can be used.

The coating layer 7 has the function of receiving and retaining charges of corona discharge in a dark place, and has the ability to transmit the light to which the charge generation layer is sensitive, and transmits the light upon exposure.
It is necessary to allow the charge to reach the charge generation layer and receive the generated charge to neutralize and eliminate the surface charge. As the coating material, organic insulating film-forming materials such as polyester and polyamide can be used. Further, these organic materials can be mixed with inorganic materials such as glass resin and SiO2, and materials that reduce electrical resistance such as metals and metal oxides. The coating material is not limited to organic insulating film forming materials, and may also be formed of inorganic materials such as SiO2, metals, metal oxides, etc. by methods such as vapor deposition and sputtering. As mentioned above, it is desirable that the coating material be as transparent as possible in the wavelength region where the charge generating substance absorbs maximum light.

The thickness of the coating layer itself depends on the composition of the coating layer, but it can be set arbitrarily within a range that does not cause any adverse effects such as an increase in residual potential when used repeatedly and continuously.

[0028]

[Operation] There is no known example of using a hydrazone compound represented by the general chemical formula (I) in a photosensitive layer. In order to achieve the above object, the present inventors conducted a number of experiments on these hydrazone compounds while intensively studying various organic materials, and found that the general chemical formula shown above is It has been shown that when a specific hydrazone compound represented by (I) consisting of two types of heterocycles containing sulfur atoms is used as a charge transport material, the charge transport ability is greatly improved and it is extremely effective in improving electrophotographic properties. As a result, we have achieved a photoreceptor with high sensitivity and excellent repeatability.

[0029]

[Example] (Example 1) x-type metal-free phthalocyanine (H
2Pc) and 100 parts by weight of the hydrazone compound represented by the above chemical formula 1 were kneaded together with 100 parts by weight of polyester resin (trade name: Vylon 200, manufactured by Toyobo) and a tetrahydrofuran (THF) solvent in a mixer for 3 hours to prepare a coating solution. was prepared and coated on an aluminum-deposited polyester film (Al-PET), which is a conductive substrate, by a wire bar method, so that the film thickness after drying was 15 μm to prepare a photoreceptor.

(Example 2) A coating liquid prepared by dissolving 80 parts by weight of the hydrazone compound represented by the chemical formula 2 and 100 parts by weight of polycarbonate resin (trade name Panlite L-1225: Teijin Chemicals) in methylene chloride was applied to aluminum. A charge transport layer was formed by coating onto a vapor-deposited polyester film substrate using a wire bar so that the film thickness after drying was 15 μm. On the thus obtained charge transport layer, 50 parts by weight of titanyl phthalocyanine (TiOPc) which had been pulverized for 150 hours in a ball mill, 50 parts by weight of a polyester resin (trade name: Vylon 200, manufactured by Toyobo), and a THF solvent were mixed for 3 hours. A coating solution was prepared by kneading with a machine, and applied with a wire bar to form a charge generation layer so that the film thickness after drying was 1 μm.

(Example 3) In Example 2, TiOP
A photoreceptor was prepared in the same manner as in Example 2 except that a squarylium compound represented by the following chemical formula 15 was used instead of c and a hydrazone compound represented by the chemical formula 3 was used as the charge transport material.

[0032]

[C6]

(Example 4) In Example 2, TiOP
Photosensitization was carried out in the same manner as in Example 2, using chlorodiane blue, which is a bisazo pigment as shown in JP-A No. 47-37543, instead of C, and changing the charge transport substance to the hydrazone compound shown by the chemical formula 4. The body was created.

The electrophotographic properties of the photoreceptor thus obtained were measured using an electrostatic recording paper tester "SP-428" manufactured by Kawaguchi Electric.
Measured using

The surface potential Vs (volts) of the photoreceptor is the initial surface potential when +6.0 kV corona discharge is performed in a dark place for 10 seconds to positively charge the photoreceptor surface, and then the corona discharge is stopped. Measure the surface potential Vd (volts) when the photoreceptor surface is held in the dark for 2 seconds, and then irradiate the surface of the photoreceptor with white light with an illuminance of 2 lux and measure the time (seconds) it takes for Vd to be halved. Determined half-attenuation exposure amount E1/
2 (looks/seconds). In addition, the surface potential when irradiated with white light with an illuminance of 2 lux for 10 seconds is the residual potential V
r (volt). In addition, for Examples 1 to 3, high sensitivity with long wavelength light can be expected, so the wavelength is 780 nm.
At the same time, the electrophotographic characteristics when using m monochromatic light were also measured. That is, measurements are taken at the same time up to Vd, then 1 μW monochromatic light (780 nm) is irradiated instead of white light to determine the half-attenuation exposure (μJ/cm2), and this light is applied to the photoreceptor surface for 10 seconds. Residual potential Vr when irradiated
(volts) was measured. The measurement results are shown in Table 1.

[0036]

[Table 1]

As seen in Table 1, Examples 1, 2, and 3
, 4 are comparable in both half-attenuation exposure and residual potential, and also exhibit good characteristics in terms of surface potential. In addition, Example 1
It can be seen that samples 3 to 3 show high sensitivity even to long wavelength light of 780 nm, and can be sufficiently used for semiconductor laser printers.

(Example 5) A charge generation layer was formed by vacuum-depositing selenium to a thickness of 1.5 μm on an aluminum plate having a thickness of 500 μm, and then 100 parts by weight of a hydrazone compound represented by the chemical formula 5 and a polycarbonate resin were deposited on an aluminum plate having a thickness of 500 μm. (PCZ200
A coating liquid prepared by dissolving 100 parts by weight of (Mitsubishi Gas Chemical) in methylene chloride was applied using a wire bar to form a charge transport layer so that the film thickness after drying was 20 μm. When this photoreceptor was corona charged at -6.0 kV for 10 seconds, VS = -680V, Vr = -15V, E1/
A good result of 2 = 2.0 lux/sec was obtained.

(Example 6) x-type metal-free phthalocyanine 5
0 parts by weight, vinyl chloride copolymer (trade name MR-110:
A coating solution was prepared by kneading 50 parts by weight of Nippon Zeon) with methylene chloride for 3 hours in a mixer, and the coating solution was coated onto an aluminum support to a thickness of about 1 μm to form a charge generation layer. Next, hydrazone compound 1 shown by chemical formula 6
00 parts by weight and polycarbonate resin (Panlite L-1
250) 100 parts by weight of silicone oil and 0.1 parts by weight of silicone oil were mixed with methylene chloride and coated on the charge generation layer to a thickness of about 15 μm to form a charge transport layer.

The photoreceptor thus obtained was used in Example 2.
When -6.0kV corona charging was performed for 10 seconds in the same manner as above, Vs = -730V, E1/2 = 1.7
Good results were obtained in terms of looks and seconds.

(Example 7) In Example 6, a bisazo pigment represented by the following chemical formula 16 was used instead of the metal-free phthalocyanine, and a hydrazone compound represented by the chemical formula 7 was used as the charge transport substance, but the same procedure as in Example 6 was carried out. A photoreceptor was created.

[0042]

[C7]

The photoreceptor thus obtained was used in Example 4.
When -6.0kV corona charging was performed for 10 seconds in the same manner as above, Vs = -770V, E1/2 = 1.5
Good results were obtained in terms of looks and seconds.

(Example 8) Photoreceptors were prepared in the same manner as in Example 4 for each of the compounds represented by chemical formulas 8 to 12, and the results of measurements using "SP-428" are shown in Table 2. Corona discharge of +6.0 kV was performed for 10 seconds in a dark place to positively charge the sample, and the half-attenuation exposure amount E1/2 (lux seconds) is shown when white light with an illuminance of 2 lux is irradiated.

[0045]

[Table 2]

As seen in Table 2, the chemical formulas 8 to 1
The half-attenuation exposure amount E1/2 was also good for the photoreceptor using the hydrazone compound represented by 2 as a charge transport material.

[0047]

[Effects of the Invention] According to the present invention, since the hydrazone compound represented by the general chemical formula (I) is used as a charge transport substance on a conductive substrate, it has high sensitivity and repeatability even in positive and negative charging. It is possible to obtain an excellent photoreceptor. In addition, a suitable charge-generating substance can be selected depending on the type of exposure light source. For example, phthalocyanine compounds, squarylium compounds, and certain bisazo compounds can be used as light-sensitive materials that can be used in semiconductor laser printers. You can get a body. Furthermore, if necessary, it is possible to provide a coating layer on the surface to improve durability.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a single-layer photoconductor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a negatively charged laminated photoreceptor according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a positively charged laminated photoreceptor according to an embodiment of the present invention.

[Explanation of symbols]

1 Conductive substrate 3 Charge generating substance 4 Charge generation layer 5 Charge transport material 6 Charge transport layer 7 Coating layer 20 Photosensitive layer 21 Photosensitive layer 22 Photosensitive layer

Claims (4)

[Claims] 1. An electrophotographic photoreceptor (in the formula R1 and R2 are hydrogen atoms, halogen atoms, and alkyl groups; R3 and R4 are each substituted or unsubstituted alkyl groups, aryl groups, and alkenyl groups; R5 and R6 are hydrogen atoms, alkyl groups, and aryl groups; R7 and R8 are each substituted or represents an unsubstituted alkyl group, aryl group, alkenyl group, or thenyl group). [Chemical formula 1] 2. The photoreceptor according to claim 1, wherein the photosensitive layer is a laminate of a charge transport layer containing a charge transport substance and a charge generation layer containing a charge generation substance. body. 3. In the photoreceptor according to claim 1, in the hydrazone compound represented by general chemical formula I, R1 and R2 are each a hydrogen atom, R5 and R6 are each a methyl group, and R3, R4 and R8 are each a phenyl group. , R7
An electrophotographic photoreceptor, characterized in that is a tenyl group. 4. In the photoreceptor according to claim 1, the hydrazone compound represented by general chemical formula I comprises R1, R2,
R5 and R6 are hydrogen atoms, R3, R4 and R
8 is a phenyl group, and R7 is a methyl group.